Problem: Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Christopher needs to master at least $53$ songs. Christopher has already mastered $17$ songs. If Christopher can master $4$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
Answer: To solve this, let's set up an expression to show how many songs Christopher will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Christopher Needs to have at least $53$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 53$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 53$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 4 + 17 \geq 53$ $ x \cdot 4 \geq 53 - 17 $ $ x \cdot 4 \geq 36 $ $x \geq \dfrac{36}{4} = 9$ Christopher must work for at least 9 months.